Heat oven to 350° F. In a medium bowl, whisk flour, sugar, baking soda, and salt.,Mix yogurt, eggs, yolks, and vanilla.,In a saucepan, combine the semisweet chocolate, oil and/or applesauce, water, cocoa, and butter. Cook over medium-low heat till you get a smooth rich sauce. Pour into large bowl that you'll eventually mix all ingredients into.,Whisk dry ingredients into hot chocolate mixture- don't over mix. Then, whisk in the egg mixture until no lumps remain.,Pour batter into a greased 13x18 baking sheet and bake for 18 to 20 minutes till tester comes out clean. If your oven has hot spots, you may want to rotate the sheet halfway through baking.,Mix butter, cream, cocoa, and corn syrup over medium heat. Melt and stir till smooth. Take off heat.,______,For bonus points, serve with whipped cream and strawberries on the side for a rich take on strawberry shortcake.